Structural Design
Alison Snead, Principals of Engineering, WTHS/PHS, Nov. 25, 2014
Final Bridge Design and Team
Design Brief
Research Summary
Most of my research consisted of notes taken in class that informed me that triangles are required to build a strong truss or bridge. This information influenced my bridge design a lot. Materials had different costs ranging from $3.78/kg to $7.95/kg. Tubes had higher costs than solid bars but weighed less, lowering the price. Each joint cost $300. Knowing the prices of materials and the strength of materials helped me chose the materials I would need to make the bridge strong but cheap.
Brainstorming Sketches
Modification Sketches
Final Bridge Design
Final Design Justification
I chose these materials and the design of my bridge for specific reasons. I chose the High-Strength Low Alloy steel because my bridge needed the strength to support the weight required. Later in my design I chose to change a few of my bars to tubes to decrease the cost of my bridge. The solid bars that remained were the members experiencing the most tension or compression. The design I chose used many different triangles. Triangles could support the weight well, but often required more materials. The bridge design and materials ensured the strength of my bridge and allowed for the problem to be solved within the constraints.
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References
I did not use any references.
Conclusion
1. The type and direction of stress applied affects the selection of the materials because with the more force applied the more strength is needed to support the force. With more stress you also want a larger cross sectional area. These factors can lead to a better modulus of elasticity and this will help the strength of the bridge.
2. Tension and compression forces work together to counteract each other. The counteraction prevents one member from experiencing too much compression or too much tension.
2. Tension and compression forces work together to counteract each other. The counteraction prevents one member from experiencing too much compression or too much tension.